NASA's New Horizons Officially Begins Its Pluto Encounter

New Horizons will make a historic flyby past Pluto next week, but there's already reason to celebrate. Today, July 7, the spacecraft switched to "flyby mode," which means the close encounter has officially begun.

ENGAGE! Data just reached the ground that New Horizons is successfully in encounter, FLYBY HAS STARTED! pic.twitter.com/MkDKArQ84T

The "flyby mode" will induce the spacecraft to fly along a predetermined course that will take it on its planned flyby, and will also allow it to automatically reboot itself if it runs into any trouble along the way. The news that New Horizons had successfully switched to flyby mode was met with cheers and applause when it reached the New Horizons team on the ground:

On July 14, New Horizons will perform a flyby at only 7,750 miles from Pluto's surface, after spending the last nine years traveling the three billion miles to the former ninth planet. The mission is expected to yield groundbreaking discoveries about the mostly mysterious dwarf planet and reveal the planet in more detail than we've ever seen it. The spacecraft experienced a worrying glitch on the Fourth of July, but after some emergency troubleshooting, the flyby managed to begin on schedule.

And in honor of the beginning of the Pluto encounter, NASA released the most up-to-date map of Pluto, made from the most recent photos taken by New Horizons from June 27 to July 3:

The long dark area to the left of the map is called the "whale," which is the darkest area visible to New Horizons. The "tail" comes into contact with a bright area called the "donut" for its circular appearance. It's unknown what either of these features actually are, hence the funny nicknames. The center of the map corresponds with the area that will be explored by New Horizons during the flyby on July 14.